Some resources on using PostgreSQL with Ruby On Rails

A blog post
on using an hstore column for storing hashes with arbitrary keys. His approach is different from the one used
in hstore_accessor gem. Aly explains how to store hashes that may have different keys for each record,
while hstore_accessor gem implies that hashed in all the records have the same keys.

Next, a very practical article on using
Postgres array columns
in Rails 4 by Plataformatec. They explain how to use an array column for storing tags.